1. Field of the Invention
The present invention relates to a fuel supply control apparatus for an engine and to a fuel supply control method therefor, and, in particular, relates to a fail-safe technology against control system malfunctions inclusive of abnormalities in signal transmission and reception.
2. Description of Related Art
Japanese Laid-open (Kokai) Patent Application Publication No. 2006-161675 discloses a fuel supply control apparatus for feedback controlling a voltage for a fuel pump to maintain fuel pressure at a target value, in which it is diagnosed based on a correction value of the voltage by the feedback control whether fuel piping is clogged or fuel has leaked out from the fuel piping.
As a fuel supply control apparatus for an engine, there has been proposed an apparatus including: an engine control unit which controls a fuel injection valve of the engine; and a fuel pump control unit which controls a fuel pump for pumping fuel to the fuel injection valve, in which the engine control unit outputs an actuating signal for the fuel pump to the fuel pump control unit. In such a fuel supply control apparatus, if abnormality occurs in input of the actuating signal in the fuel pump control unit, a fuel pressure control is not normally performed. Therefore, it is preferable that a diagnostic signal indicating that the abnormality occurs in the input of the actuating signal be transmitted from the fuel pump control unit to the engine control unit, to thereby perform a fail-safe function in the engine control unit.
As the fail-safe function in the fuel supply control apparatus, the stopping of the fuel pump is performed or the stopping of injection by the fuel injection valve is performed. However, if an operation of the fuel pump or the fuel injection valve is stopped against control system malfunctions inclusive of abnormalities in signal transmission and reception between units, in the case of a vehicle engine, the vehicle running is likely not to be performed.